a) Field of the Invention
The present invention relates to data communications technologies, and more particularly to real time data communications technologies. A “real time” response to an event is essentially simultaneous with the event itself. However, in communications, because of time delay for transmission time, signal synchronization, other necessary signal process or the like, “real time” does not mean strictly simultaneous.
b) Description of the Related Art
As a standard specification for communications between electronic musical instruments, a music instrumental digital interface (MIDI) specification is known. Electronic musical instruments equipped with interfaces of the MIDI specification can communicate with each other by transferring MIDI data via a MIDI cable.
For example, an electronic musical instrument transmits MIDI data of a musical performance by a player, and another musical instrument receives it to reproduce it. As one electronic musical instrument is played, another electronic musical instrument can be played in real time.
In a communications network interconnecting a plurality of general computers, various types of data are transferred. For example, live musical tone data or other MIDI data can be transmitted from one computer, which once stored the data in its storage device such as a hard disk, via the communications network to another computer which stores the received data in its storage device. A general communications network is, however, configured to perform only general data communications, and is not configured to properly process MIDI data.
Specifically, although the MIDI specification allows the “real time” communications to be performed between electronic musical instruments, it is not suitable for long distance communications and communications via a number of nodes. The general communications network is essentially configured to provide services of long distance communications and multiple-node communications, but it does not take account of “real time” communications between electronic musical instruments.
Real time communications of musical information uses a large amount of information per unit time, and the traffic of the communications line becomes heavy. As compared to point-to-point communications, point-to-multipoint communications of musical tone data is more likely to make the traffic of communications lines heavy. The heavy traffic of communications lines generates a transmission delay and hinders a real time musical performance.